The present invention generally relates to an apparatus for sorting lumber pieces, wherein lumber pieces having similar characteristics are dropped in one of a plurality of consecutive sort bins which are disposed one after the other. More particularly, it relates to a sort bin for unloading sorted lumber pieces on a conveyor.
Commonly used in lumber mills, there are apparatuses, called lumber sorters, used for sorting lumber pieces according to their characteristics, such as their section (ex. 1xc3x973, 2xc3x974, 2xc3x976, etc.), their length or their general appearance. Known lumber sorters generally comprise a plurality of consecutive sort bins, each having an entry at an upper end portion for receiving lumber pieces dropped from an upper conveyor. A support movable between a raised position and a lower position is usually provided between the walls of each sort bin for supporting the lumber pieces therein. The support lowers gradually as the sort bin is filled up with more lumber pieces. When a given quantity of lumber pieces has been collected in a sort bin, this quantity is unloaded on a conveyor situated beneath the sort bin and spaced apart therefrom to be transported to a location where the lumber pieces are further handled. Referring to FIG. 6, an example of a prior art lumber sorter is illustrated. The sorter (200) comprises a plurality of consecutive sort bins (210) (only four of which are designated with the numeral reference 210). Each sort bin (210) has an entry at an upper end thereof for receiving lumber pieces (4) directed over the sorter (200) by means of an upper conveyor (218), such as a lug chain conveyor, as illustrated. More particularly, in the sorter (200) illustrated, a floor extending over the sorter (200) supports the unsorted lumber pieces (4) as they are being pushed by the lug chain conveyor (218). A controllable trap opening (220) in the floor is provided over the entry of each sort bin (210). When a lumber piece (4) reaches its respective sort bin (210), the corresponding trap opening (220) opens and the lumber piece (4) falls into the sort bin on a support (222) extending between the walls of the sort bin (210). The support (222) lowers gradually as the sort bin (210) is filled up with more lumber pieces (4) and until it reaches an unloading conveyor (224) disposed below the sort bin (210) spaced apart therefrom. Then, the lumber pieces (4) are discharged on the unloading conveyor (224) and directed to another lumber station (230) such as, for example, a pile station. As can be appreciated from FIG. 6, when the support (222) lowers further below the lower end of the sort bin (210), as in the sort bin designated by numeral reference (210a), there is no more lateral support for the lumber pieces (4) at the bottom of the pile, which thus tend to spill out and fall on the unloading conveyor (224), and that, before the support (222) has reached the unloading conveyor (224). One drawback is that sometimes, one ore more of those spilled lumber pieces end up under the support (222) (see sort bin 210a) and get trapped between the conveyor (224) and the support (222), which often causes a stop in the production.
Prior attempts to resolve that problem are disclosed for example in U.S. Pat. No. 4,815,917 or 4,195,737. U.S. Pat. No. 4,815,917 discloses a bin sorter with a plurality of sort bins, each having a bin floor which can be lowered to a lumber discharge station and a series of rotatable gates extending from the bottom of each bin wall and functioning to control the discharge of lumber from the individual bins; and U.S. Pat. No. 4,195,737 discloses a bin sorter with a plurality of inclined bins with pivotable gates extending from the bottom of each bin wall.
Other examples of bin sorters for lumber pieces are given in the following U.S. Pat. Nos. 2,998,133; 3,696,948; 3,913,744; and 4,281,953.
An object of the present invention is to propose a sort bin that can inexpensively and efficiently sort lumber pieces.
Another object of the invention is to propose a sort bin that can efficiently prevent stops in the production caused by spillage of the lumber pieces.
In accordance with the present invention, these objects are achieved with a sort bin for unloading sorted lumber pieces on a conveyor. The sort bin comprises a compartment having first and second spaced-apart walls for containing the lumber pieces in a pile, an entry located at an upper portion of the compartment for introducing lumber pieces into the compartment and an exit located at a bottom portion of the compartment, the conveyor being below the exit and spaced apart therefrom. The sort bin further comprises a support for supporting the pile of lumber pieces contained in the compartment, the support being movable along a course extending between an upper position adjacent to the entry and a lower position below the exit of the compartment. The support has side members for preventing a spill of lumber pieces on the conveyor when the support is in its lower position, one of the side members being pivotable between a standard position and an unloading position. The sort bin also comprises means for moving the support between the upper and lower positions and pivoting means for pivoting the pivotable side member of the support between the standard position where a bottom end portion of the pile is held and the unloading position where the lumber pieces of the pile are unloaded on the conveyor.
The present invention also concerns a sorter for lumber pieces comprising a plurality of consecutive sort bins as described above.
The invention and its advantages will be better understood upon reading the non restrictive description of a preferred embodiment of the present invention. This description is given with reference to the appended drawings.